Gun order converter



June 11, 1957 c. H. DOWKER ETAL 2,795,379

GUN ORDER CONVERTER Filed June 1, 1949 18 Sheets-Sheet 1 B'r' DIRECTORTRAIN 5' mmzcron ELEVATION OP -PRESENT RANGE (R) LINE OF SICROSS-TRAVERSE PLANE FIG. IB

' do? -PRESENT RANGE (R) STA TA dSs- \LSTASTAEEELZ 2333K: 'T' kml REEHDOWKER dR =INSTANTANEOU$ RANGE RATE June 1957 c. H. DOWKER ETAL GUNQRDER CONVERTER l8 Sheets-Sheet 2 Filed June 1, 1949 FIG. 10

PLANE PERPENDICULAR 7|NE OF SIGHT dHfpCosE-T2 dHfpsinE'Tz gvwe/w'im R.5. PHILLIPS G. H. DOW/(ER C. H. DOWKER ETM.

GUN ORDER CONVERTER June 11, 1957 Filed June 1, 1949 18 Sheets-Sheet 3FIG. IE P2 I I: F! RdBs'Tz V'd v I I I/ E Us {I j r i F /6. IF F1 LINEor FLIGHT g 2 545mm LINE/0F FLIEFr x ERROR R awe/rm RSPH/LL/PS QHDUWKERJune 11, 1957 c. H. DOWKER ETAL GUN ORDER CONVERTER Filed June 1, 1949'18 Shasta-Sheet 4 FIG. IJ

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June 11, 1957 c. H. DOWKER ETAL 2,795,379

GUN ORDER CONVERTER Filed June 1, 1949 18 Sheets-She 10 256 256 Moviesg/v 293 VIBRATOR (250 CAT/100E SERVO FILTER rauawsn AMPLIFIER 297 30! fl 29I no me, 342 i 60 v v 292 318 3pg .621 maps ssnvo FILTER 29aFOLLOWER AMPLIFIER wamron 24a 26| |o| 294 26l w [262 I10 v4.0. so [25zjvwwvbom 35 R5. PHILLIPS 6. HDOWKER M Xfl fl June 11, 1957 c. H. DOWKERETAL GUN ORDER CONVERTER 18 Sheets-Sheet 11 Filed June 1, 1949 3mm 5. 5.PH/LL IPS 61H DOW/(ER GUN ORDER CONVERTER 18 Sheets-Sheet 12 Filed June1, 1949 M s m M m m D w 0 m v w D E W K H 0 W Y \H .0 W E W F IG. 4

Ill!- SQUARE POTENTIOMETER June 11, 1957 c. H. DOWKER ETAL 2,795,379

GUN ORDER CONVERTER Filed June 1, 1949 18 Sheets-Sheet. 13

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LINE OF SIGH CROSS TRAVERSE CROSS TRAVERSE AXIS VERTICAL LINE GUNTHROUGH DIRECTOR BARR EL AXIS DIRECTOR TRAIN ELEVATION AXIS GUNELEVATION AXIS INVENTOR R. 5'. PH/LL/PS BY 0.11.0 WKER j 0 MTTORNEY June11, 1957 c. H. DOWKER ETAL GUN ORDER CONVERTER 18 Sheets-Sheet 14 FiledJune 1. 1949 DIRECTOR TRAIN AXIS ELEVATED POSITION) R O T O E m D TRAINAXIS (ZERO ELEVATION POSITION) LINE OF SIGHT, cans TRAVERSE A sum BARRELDECK PLANE D IREO TOR TRAVERSE P LAN E DIRECTOR 7 ELEVATION AXIS GUN 5ELEVATION AXIS cRd at" GROSS TRAVERSE PLANE R. 5. PH/L L IPS BYGil/.DOWKER ATTORNEY June 11, 1957 c. H. DOWKER ETAL 2,795,379

GUN ORDER CONVERTER Filed June 1, 1949 18 Sheets-Sheet 15 GUN ELEVATIONDECK PLANE AXIS (OF AXIS CONVERTER) euu TRAIN T AXIS DIRECTOR TRAVERSE'mREToR ELEVA non VOLTAGE AT PoT. ;g NTAcT= GROSS TRAVERSE PLANE GUNBARREL AXIS INVENTOR Rap/111.1. /P8

6. H. DOW/(ER June 1957 c. H. DOWKER ETAL 2,795,379

GUN ORDER CONVERTER Filed June 1, 1949 18 Sheets-Sheet 16 dHfp 0055 June11, 1957 c. H. DOWKER ETAL GUN ORDER CONVERTER l8 Sheets-Sheet 18 FiledJune 1, 1949 R. s. P/3 IZ Z /Ps BY (ZHDOWKER ATTORNEY 2,795,379 PatentedJune 11, 1957 GUN ORDER CONVERTER Clill'ord Hugh Dowker, Princeton, N.J., and Ralph S.

Phillips, Los Angeles, Calif., assignors, by mesne assignments, to theUnited States of America as represented by the Secretary of the NavyApplication June 1, 1949, Serial No. 96,516

23 Claims. (Cl. 235-61.5)

This invention relates to improvements in gun order converters for usein gun fire control systems employing a gun director for training andfiring a gun at a moving target, and more particularly to gun orderconverters of the type in which a movable member is employed and movedin a manner simulating the movements of the target to thereby maintainthe member in a position corresponding to the desired lead angles oftarget motion, and has associated therewith means for obtainingelectrical signals representing said position.

In accordance with a preferred embodiment of the instant invention, apair of rectangularly wound tapered potentiometers disposed in mutuallyperpendicular directions have their arms positioned in mannerscorresponding to the lead angles of the target in a pair of mutuallyperpendicular directions corresponding to true traverse and trueelevation. Voltages derived from the potentiometers are employed in apair of servo systems for positioning a finger to which the contact armsof the potentiometers are operatively connected, and are also employed,in conjunction with target present position information from thedirector, to obtain gun orders.

Apparatus embodying the instant invention also includes mean forcompensating for the roll and pitch of the vessel and means forcompensating for the time by which target rate data is late due tosmoothing.

The apparatus of the instant invention also provides for a fire controlarrangement in which it is unnecessary to compute the quantity T2, ortime of flight of the projectile to the future position of the target,and corresponding quantities U3 or U, shell average velocity along therange component of future position, quantities which it has been founddifficult to compute, but permits a ballistic computed quantity U, orcomputational shell velocity, to be employed instead of U3 or U in thecomputing circuits. This is accomplished by tapering the aforementionedpotentiometers in a manner to be subsequently described.

The instant invention is particularly well adapted for use in the gunfire control system described and claimed in the copending applicationof Ivan A. Getting for Gun Fire Control Method and System, Serial No.61,558, filed November 23, 1948.

An object of the invention is to provide new and improved gun orderconverter apparatus.

Another object is to provide new and improved gun order converterapparatus employing a finger which is continuously positioned inaccordance with the lead angles of a moving target.

Another object is to provide new and improved gun order converterapparatus in which time of flight computation is eliminated.

Another object is to provide new and improved gun order converterapparatus for use aboard a vessel in which rotation of the deck as thevessel rolls and pitches is corrected for.

Another object is to provide new and improved gun order converterapparatus in which the etlects of wind upon the projectile are correctedfor.

Another object is to provide new and improved gun order converterapparatus in which the effect of gravity upon the projectile iscorrected for.

Still another object is to provide new and improved gun order converterapparatus in which the elfect of drift of the projectile is correctedfor.

A further object of the invention is to Provide new and improved gunorder converter apparatus in which smoothed rate data is employed andthe effects of smoothing corrected for.

Other objects and advantages of the instant invention will become moreclearly apparent after perusal of the following specification, taken inconjunction with the accompanying drawings, in which:

Figs. lA-lK inclusive are simplified geometrical diagrams illustratingthe operation of the invention;

Fig. 2 is a block diagram of a gun fire control system utilizing theinstant invention;

Figs. 3A through 3F inclusive taken together comprise a schematicdiagram of electrical apparatus including a director and gun orderconverter embodying the instant invention;

Fig. 4 is a view of an angle converter constructed according to theinstant invention;

Figs. 5A through 5C are geometrical diagrams illustrating the operationof the apparatus of the instant invention; and

Figs. 6A, 6B, and 6C taken together comprise a view of a mechanicalballistic computer suitable for use with the instant invention.

In the description of the invention, the following nomenclature isemployed:

B'gr-Gun train. The angle between the fore and aft axis of own ship andthe plane through the gun perpendicular to the deck, measured in thedeck plane clockwise from the bow.

B'grp-Gun train order corrected for horizontal parallax of the directorto the reference point of the ship.

B'r-Director train in slant plane parallel to deck.

Br'-Director train. The angle between the fore and aft axis of own shipand the plane through the line of sight perpendicular to the deck,measured in the deck plane clockwise from the bow.

B'r'pDirector train corrected for horizontal parallax to the referencepoint of the ship.

BwTrue direction of true wind. The angle between north and the directionfrom which the true wind is blowing, measured in a horizontal planeclockwise from north.

cBefore a quantity indicates a generated voltage corresponding to thatquantity and used for nulling purposes or for obtaining an error signal.

Co--Own ship course. The angle between the north and south verticalplane and the vertical plane through the fore and aft axis of own shipmeasured in a horizontal plane clockwise from the bow.

D-Traverse deflection. The angle between the line of sight and the planethrough the gun perpendicular to the traverse plane, measured in thetraverse plane clockwise from the line of sight.

dBs-Angular traverse rate. The time rate of change of true targetbearing measured in the traverse plane.

D'sDeflection in the slant plane.

D'd-Deck deflection. Gun train order minus director train.

dEAngular elevation rate. of target elevation.

dHfp-Gravity drop rate corrected for vertical parallax.

dHfp=k24.k25G+k4c i Ii tw.

dR-Range rate. The time rate of change of range.

The time rate of change (Further distinguished by the subscript "t asdRt when used in combination with range rate correction terms.)

dRtwComputational range rate. Range rate for the computation of averageshell velocity: the sum of the smoothed range rate cTR due to relativemotion of the target 2 and a corrective term, dRw, applied to range ratedR to compensate for the effect on shell velocity due to the componentof relative wind w which lies along the line of sight.

dRw-Range rate correction due to line of sight wind. A correction termapplied to range rate to compensate for the effect on shell velocity dueto the component of relative wind which lies along the line of sight.

eBefore a quantity denotes the instantaneous error in the quantity.

ETarget elevation. The elevation above the horizontal plane of the lineof sight, measured in the vertical plane through the line of sight.

EbDirector elevation. The elevation of the director line of sight abovethe deck, measured in a plane perpendicular to the deck, through theline of sight. The indicates that the quantity is taken relative to thedeck while the b refers to the director.

E'gGun elevation order. The elevation of the gun above the deck measuredin a plane through the gun perpendicular to the deck, while theindicates the quantity is taken relative to the deck and the g indicatesthat it refers to the gun.

F-Fuze setting. Fuze setting in seconds.

G-Cornputational time of flight. Time of flight to a hypothetical targetwhich is following a radial path with a velocity equal to the range rateof the real target.

Ph-Horizontal parallax. The angular correction to be applied to guntrain order for a gun which is 100 yards fore of the reference point.

RRange. The distance in yards from the director to the target (measuredalong the line of sight).

R2-Future range. The range at which the target will be when theprojectile now being fired bursts, where the subscript "2 indicates thefuture position.

RdBsLinear traverse rate. The component of the linear cross rate lyingin the traverse plane, where 19 indicates the quantity as is takenrelative to the line of sight. (Further distinguished by the subscript"1 as RdBst when used in combination with linear traverse ratecorrection terms to indicate motion relative to the target.)

RdBsf-Linear traverse rate correction due to drift. A correction termapplied to linear traverse rate to compensate for the efiect of drift ofthe projectile, where f indicates a movement relative to the standardtrajectory. Sui a movement is called drift.

RdBstfwComputational linear traverse rate. Linear traverse rate for thecomputation of lead angle: the sum of the smoothed linear traverse ratelTs due to relative motion of the target I, a corrective term tocompensate for the effect of drift RdBsf, and a corrective term tocompensate for the effect of cross wind, RdBsw.

RdBswLinear traverse rate correction due to cross wind. A correctionterm applied to linear traverse rate to compensate for the effect onshell velocity due to the cross wind, where R is a range, aB" is rate oftraverse, s is relative to the line of sight, and "w is due to the wind.

RdELinear elevation rate. The component of the linear cross rate lyingin a vertical plane through the line of sight. (Further distinguished bythe subscript "1 as RdEr when used in combination with linear elevationrate correction terms.)

RdEfp-Linear elevation rate correction due to gravity drop rate andvertical parallax. A correction term applied to linear elevation rate tocompensate for the effect of gravity drop rate and vertical parallax.

4 RdEfp=dHfp cos E Editfpw-omputational linear elevation rate. Linearelevation rate for the computation of lead angle: The sum of thesmoothed linear elevation rate Ell 3 due to relative motion of thetarget 2, a corrective term p to compensate for the effect of gravitydrop and vertical parallax, and a corrective term w to compensate forthe effect of relative wind perpendicular to the line of sight in avertical plane. RdEtfpw=m+RdEw+RdEfn RdEw-Linear elevation ratecorrection due to elevation wind. A correction term applied to linearelevation rate to compensate for the effect on shell velocity due to thecomponent of relative wind perpendicular to the line of sight in avertical plane.

S0'Own ship speed. The speed of own ship relative to the earth.

Sw-True Wind speed. The horizontal velocity of true Wind with respect tothe earth.

T2Time of flight to future position of target.

TgDead time. The time in seconds between cutting a fuze and firing theprojectile.

TqSmoothing time. The time by which linear traverse rate and linearelevation rate may be considered to be late due to smoothing.

UMeasured average shell velocity. The average shell velocity over therange interval 1,000 to 3,000 yards with zero gun elevation and no wind.

UAverage shell velocity for lead angle computation.

U0A shell velocity employed in fuze computation.

UtU prediction. The increment of U which must be included to takeaccount of target motion during time of flight where the subscript "1"indicates that the motion is related to the target.

U1Average shell velocity to present position of the target, where "1indicates present position.

U2-Average shell velocity. The quotient of range to future positiondivided by time of flight, where 2 indicates the future position.

U3 equals fl corrected for parallax.

VVertical deflection angle. The angle between the line of sight and theplane through the gun perpendicular to the vertical plane through theline of sight measured in the vertical plane through the line of sight,positive when the gun is above the line of sight.

V'dElevation difference. Gun elevation order minus director elevation,Where the indicates that the quantity is taken relative to the deck andthe d following the quantity indicates that the quantity is measured inplane perpendicular to the deck.

Zq-Smoothing rotation about the line of sight. A rotation increment ofthe grid of the gun order converter about the line of sight necessary tocorrect for the smooth ing of the linear traverse and elevation rates.It is equal to Tq-dBs'tan E, and is measured clockwise about the line ofsight.

Zs-Cross traverse. The angle, measured in a plane perpendicular to theline of sight s, between a vertical plane through the line of sight anda plane perpendicular to the deck through the line of sight. (Positivefor the purposes of computation if, when you face the target. the righthand side of the ship is up.)

Zsqu-Computational rotation about the line of sight. The sum of crosstraverse, smoothing rotation about the line of sight, and a correctiveterm.

ZuA correction to cross traverse.

The following terms, when used to modify a basic

